1. Field of the Invention
The present invention relates to a feeder for collecting printed sheets in an astride position. The feeder includes a pulling-off drum which has at the circumference thereof gripping means for pulling off printed sheets stacked in a magazine. The feeder further includes means for conveying the printed sheets with an open side facing forward into an opening device. The opening device is arranged in front of a collecting device.
2. Description of the Related Art
Feeders of the above-described type have a pulling-off drum which has at the circumference thereof gripping members which serve to pull the individual sheets from a stack and to convey the sheets to opening drums. The pulling-off drum grasps the sheets at their closed backs and conveys the sheets to a stationary pocket arranged at the circumference of the drum, wherein the sheets come to rest against a stop in the pocket. Additional gripping means are provided for grasping the sheets at their open ends and for pulling the sheets against the direction of rotation of the drum out of the pocket and to convey the sheets to the opening drums where they are opened and placed on the collector chain.
In the feeder of this type, a precise contact or impact of the sheets at the stationary stops of the pocket is no longer ensured at very high speeds because the sheets can no longer come to rest in the pocket. When the sheets are not precisely placed in the pocket, they cannot be exactly grasped with the additional gripping means at the open ends and can subsequently not be safely opened in the opening drums. This means that a further increase of the output is not possible.
Therefore, it is the primary object of the present invention to provide a feeder of the above-described type which ensures a high output and which can still be manufactured inexpensively and operates safely.
In accordance with the present invention, the means arranged between the pulling-off drum and the opening device is formed by a pocket wheel or a pocket chain provided with revolving pockets for receiving the printed sheets which are supplied with their folds facing forwardly, and a conveying member arranged in front of the pockets.
As a result of the configuration according to the present invention, the use of several pockets makes it possible that the sheets can remain in the pockets for a much longer time. Consequently, there is enough time for the sheets to come to rest in the pockets and, if necessary, for the sheets to be precisely aligned. Thus, the sheets which have come to rest in the pockets can be conveyed precisely to the opening drums even at higher processing speeds.
Another advantage of the feeder according to the present invention is seen in the fact that sheets can be supplied with several pulling-off drums. In that case, one of the pulling-off drums can be used, for example, as a repair element or in a 2:1 operation for facilitating the manual feeding by several persons. Also possible is a selective production in which different sheets are conveyed in a controlled manner from several stacks. In addition, one of the pulling-off drums can be used for automatic feeding and another pulling-off drum can be used for a manual reinsertion of the sheets.
The various features of novelty which characterize the invention are pointed out with particularity in the claims annexed to and forming a part of the disclosure. For a better understanding of the invention, its operating advantages, specific objects attained by its use, reference should be had to the drawing and descriptive matter in which there are illustrated and described preferred embodiments of the invention.